Hi all, I'm a novice in audio system and I have an Oppo PM-3 headphone for a few years aready. A friend of mine just gave me an article about balanced cable a few weeks ago and I'm very much interested in it since PM-3 supports balanced system using 3.5mm TRRS (4 poles, 4 conductors, 4 positions, or any other name) with the composition : Tip (L+), Ring (R+), Ring (L-), Sleeve (R-) (please correct me if it in the wrong order). But then I found balanced system really cost a lot, so I want to at least solder the cable myself. One thing I'm still confused is that while TRRS balanced cabling only have L+, R+, L-, and R- connections (without Ground connection) then why is RCA cabling that have the same connections not a balanced system? If I have a shielded cable can I just screw the shield on the amp's body and got it grounded even on RCA connection? Or maybe the main question is : is there any workaround to make RCA connection become a balanced system? Because real balance amp is usually very expensive. Thank you very much in advance.